OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2278

O2 Sensor Signals Swapped Bank 1 Sensor 3 / Bank 2 Sensor 3

The PCM detects that the O2 sensor signals from bank 1 sensor 3 and bank 2 sensor 3 are swapped — typically a wiring crossover after sensor replacement.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number2 / 78

Possible causes

  • Wiring crossover after sensor replacement high

Symptoms

  • Check engine light on
  • Increased fuel consumption
  • Possible rough idle or hesitation
  • Failed emissions test

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 10–100 €
  • Estimated time: 0.2–1 h
  • Component: oxygen sensor
  • MIL / check engine light
  • emissions-relevant

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication